BL> Have you ever worked on a TV PC board as old as 25 years? Is
BL> that what happens in the end? I've never heard of this sort of
BL> thing... it's almost as if the wire has corroded *inside* the
BL> solder.

RM> I've seen quite a few joints that resemble this - the solder
RM> looks fine, even shiny, obviously not "dry", but the wire
RM> inside has disconnected itself from the solder surrounding it.
RM> Maybe the wire has swollen and shrunk often enough to work its
RM> way free of the solder, or maybe it's a long term corrosion
RM> thing, I'm not sure.

 That's exactly the effect. The solder joint seems perfect, there is
no sign of crystallising, but the wire is loose (and corroded) and it
is hellish difficult to get the lead to tin. In one case I had to take
the resistor out and file the lead back to bare copper.

 So far, all these dry joints are in the 2-amp 16KHz circuitry. I
ended up resoldering the lot (and still missed one). The TV set is
working again after FIVE! separate faults. The weird part is that some
of the leads are tinned copper (resistors, capacitors, coils) and some
are silvered brass (socket pins).

RM> -!- "The future isn't what it used to be" - Yogi Berra

... "I'm smarter than the average bear" - Yogi Bear

BTW, your end quotes are coming out as tear lines with "--- " in front 
instead of "... "

Regards,
Bob

 

--- BQWK Alpha 0.5